Ototoxic drugs

What it is

Ototoxicity causes SNHL with tinnitus. It is a drug effect, so the whole of it is a list of drugs and of whether the loss comes back.

The drugs, and which loss is permanent

• Aminoglycosides (Gentamicin): irreversible, permanent SNHL. The pathophysiology is irreversible destruction of outer hair cells in the organ of Corti
• Chemotherapy: the worst is cisplatin, and it is irreversible
• Streptomycin, the bactericidal anti-tuberculous drug given 1 gm I.M daily: ototoxic, irreversible
• Antimalarials (Quinines): hearing loss with tinnitus, reversible if discontinued, but can lead to permanent loss
• Salicylates (Aspirin): large doses, generally reversible
• NSAIDs: Naproxen
• Furosemide

So the split is not tidy. Aminoglycosides and cisplatin do not come back; aspirin does; and the quinines come back if discontinued yet can still end in permanent loss.

Causes and risk

For the aminoglycosides the risk factors are large doses, high blood levels, or long duration of therapy, elderly, and preexisting hearing impairment.

Among those, duration of treatment is the most important predictor of ototoxicity.